Ultrasonic relaxation techniques will be applied to the problem of the syn-anti glycosyl conformation of nucleosides in aqueous solution. In the coming year the ultrasonic behavior of the following systems will be investigated: a. 2'-deoxyadenosine in H2O and in H2O - urea. b. adenosine-3', 5'-cyclicmonophosphate in the presence of tryptophan binding. c. intermediates in ribonuclease A hydrolysis: 3'-cytidinemonophosphate and 2', 3'-cytidine cyclicmonophosphate.